Is it possible to make plastic from Jerusalem artichokes? The question may sound strange but it is possible, as Professor Bo Mattiasson can attest. Mattiasson is one of the initiators of a unique bio-refinery that opened in the summer of 2012. It plays an important role in the development of processes to produce chemicals, fuels and other products from bio-based raw materials.
“A bio-refinery can be compared to an oil refinery, in which crude oil is refined to different products. However, there are fundamental differences in the techniques and the most important is related to the raw materials that are used,” says Josefin Ahlqvist, project manager for the bio-refinery in Öresund, Sweden. “Jerusalem artichokes are an example of a raw material which can be used in a bio-refinery. Sugar beets, sugar cane wheat, potatoes, rapeseed, forestry waste and agricultural residues are other examples of possible ingredients. Everything has a biological origin and compared with the fossil raw materials in an oil refinery the carbon footprint is much lower. The end products – such as plastics, fuels and chemicals – can be exactly the same regardless of the technology used.”
“There are many research groups worldwide working to convert renewable materials into valuable products. However, there is a lot that must fall into place for a bio-refinery to be a commercial success. The price of the raw materials should be low and the availability high, the environmental impact of the cultivation and refining must be low and the conversion from raw material to finished product must be effective. These factors must interact in order to be able to compete with traditional chemical methods.”
“In the Swedish – Danish project Bio-refinery Öresund, we work broadly with refining processes at the Anneberg farm in Skåne. This gives us the ability to test different materials, enzyme systems and processes on a pilot scale.”
Plastic from Jerusalem artichokes?
“A Jerusalem artichoke is a plant that grows underground and contains a polymer called inulin, which is made up of fructose,” said Bo Mattiasson during a lecture for the UR radio program in Sweden. “It is good to make soup of them but even the above-ground parts of the plant contain useful chemicals. The plant can be grown over large areas and there is every reason to use the parts that do not end up on the dinner table.”
Mattiasson and his colleagues use the Halomonas boliviensis bacteria to produce polyhydric acid (PHB). The bacteria was found in Laguna Lake Colorada at 4,000 meters altitude in Bolivia. The bacteria was shipped to Lund and is an example of how living organisms can be used to produce chemicals for industry.
A colony of Halomonas is placed in a special vessel (to ferment) and with the appropriate nutritional – e.g. fructose from the shanks of artichokes – it can grow rapidly. The bacterium contains a particular enzyme that catalyzes the production of PHB.
Approximately 80 percent of the bacterial dry weight will eventually consist of polyhydric acid. This polymer can then be purified and used as a raw material for biodegradable plastics.
“Another example is the sugar glucose which with the help of biotechnology can be converted into propionic acid, lactic acid, ethanol, butanol, and more. These types of molecules are of great interest to the chemical industry, which uses them as basic chemicals to make lots of different products,” explains Mattiasson. “Currently we are working to produce propionic acid, which in turn can be used to produce acrylic acid which is used to produce acrylic plastics.”
“We see lots of possibilities and are constantly on the lookout for bacteria and other microorganisms that can act as bio-catalysts. We are often in extreme environments such as hot springs, arctic areas or in salt-rich environments,” adds Mattiasson. “If we are lucky, the microorganisms will do what we want and can be used in our fermenters. Sometimes we see that they have exactly the enzyme system we are looking for. Then we have the opportunity to enter the microorganism’s DNA in order to pick out the gene that produces the enzyme of interest and assemble the gene into another organism.”
Trials on a realistic scale
Once researchers have found a suitable bio-catalyst, it is time for the bio-refinery. The new pilot plant in Anneberg will provide researchers and industrial clients opportunities to make attempts on a realistic scale. The facility will also be available for teaching purposes. The core of the bio-refinery is a number of tanks in sizes from a few hundred litres to 10 cubic meters. In a first step, the plants are ground down to a “soup.”
Depending on the end product that one wants, bio-catalysts are added, i.e. microorganisms with specific enzyme systems. The microorganisms utilize the substrate and convert the biomass into new molecules that can be purified and used in many different ways.
“Obviously, we focus on the end product that we want in the bio-refinery, but we also think of how we can best utilize what is left in the biochemical processes. It may be unused material, products or unwanted products formed by the wrong bacteria,” says Mattiasson. “We throw nothing away but use the leftovers for the production of biogas. A portion of the biogas produced can be used for example for the biogas used by project personnel in their cars. We also get a fertilizer. We try to think of how to utilize biomass for the production of chemicals and materials – that is where the big money is – but it is also important to utilize the by-products in an environmentally sound manner,” concludes Mattiasson.
The article was published in October 2013